1. Field of the Invention
The present invention relates to an image display apparatus suitable for a head mount type display and an electronic viewfinder system, etc.
2. Related Background Art
Currently, as image display in an electronic viewfinder system such as head mount type display apparatus or a digital camera etc., a two-dimensional display element called as a flat panel display such as a transmission type liquid crystal, reflection type liquid crystal or an organic EL element etc. are used. And combining these two-dimensional display elements with an eyepiece optical system (ocular optical system), the display image is observed as a virtual image.
In recent years, further highly fine image display is required for such an image display apparatus. Therefore, production of a great number of pixels on a flat panel display is required.
In general, an increase in pixel counts leads to increase in pixel defect. In addition, the pixel size gets small relatively with size of the flat panel to make production thereof difficult.
In addition, such an image display apparatus of causing an observer to recognize a two-dimensional image visually with a scanning member without using any two-dimensional image display element is known as well (U.S. Pat. No. 5,467,104).
U.S. Pat. No. 5,467,104 describes technology of scanning a retina in the horizontal direction and the perpendicular direction with the respective colors of Red, Green and Blue light to directly form an image onto the retina through an optical system.
In addition, for a scanning type image display apparatus, a method of enlarging a small exit pupil diameter is proposed (U.S. Pat. Nos. 5,701,132 and 5,767,544).
The other scanning type image display apparatuses are proposed as well (Japanese Patent Application Laid-Open No. 2001-004955, Japanese Patent Application Laid-Open No. 2001-194617 and Japanese Patent Application Laid-Open No. H11-125791 (corresponding to U.S. Pat. No. 6,333,820).
On the other hand, with progress in semiconductor processing, such a technology of producing a small and light in weight but rapid scanning member with a Micro Electro Mechanical SYSTEM (MEWS) has been proposed (Japanese Patent Application Laid-Open H07-175005 (corresponding to U.S. Pat. No. 5,606,447) and Japanese Patent Application Laid-Open No. H08-334723).